1. Field of the Invention
The present invention relates to a liquid crystal module.
2. Background Information
With a direct backlight type of liquid crystal module in which the light source is disposed along the back of a liquid crystal panel, the liquid crystal panel is disposed on the front side of the casing of the liquid crystal module, a diffuser plate is disposed on the back side of the casing, and the space inside the casing in which the light source is disposed is sealed off at this diffuser plate.
One way in which the space inside the casing is sealed off is with an adhesive tape. The gap at the attachment portion between the liquid crystal panel and diffuser plate and the casing is closed with an adhesive tape, which prevents dust from getting into the casing. However, using an adhesive tape results in additional manufacturing cost and also requires a process of attaching the tape.
Another way to close the space inside the casing is to fit the diffuser plate onto a catch provided to the casing, and attach the liquid crystal panel so as to cover the diffuser plate. This method reduces manufacturing cost, improves the work efficiency, and also prevents warping of the diffuser plate.
When this method is employed, however, it is difficult to prevent dust infiltration. In general, the casing portion of a liquid crystal module is molded from a resin in a mold. When the catch, onto which the diffuser plate is fitted, is molded, through holes that go through the casing are also formed automatically near the catch. It is possible that dust from the outside could get inside the liquid crystal module through these through holes. In particular, since there is a gap between the diffuser plate and the catch, dust can get in through this gap, which means that dust can work its way inside the space between the liquid crystal panel and the diffuser plate. When dusts are inside the space, such dust can show through the liquid crystal panel during the use of the liquid crystal panel, and lead to defects in the liquid crystal display.
As a means for preventing dust from entering inside a liquid crystal module, for example, Japanese Patent Application Publication No. 2003-162901 (P. 5, FIG. 4) discloses a liquid crystal display device having a structure in which the gap between the diffuser plate and the frame portion of the casing is sealed off with a sealing member, and a structure in which the gap between the liquid crystal panel and the frame member is sealed off with a spacer member. Japanese Patent Application Publication No. H5-107529 (p. 2, FIGS. 1, 2, and 4) discloses a liquid crystal display device having a structure in which an elastic member is disposed at the gap between the liquid crystal panel and the backlight. Japanese Patent Application Publication No. H6-139766 (p. 3, FIGS. 1 to 3 and FIG. 6.) discloses prevention of dust from getting into a housing disposed inside an optical information recording and reproduction device. Japanese Patent Application Publication No. H6-139766 discloses a structure in which an insulating member and a circuit board are attached in that order so as to cover substantially the entire bottom of the housing, and the openings formed in the circuit board are sealed off with soldering.
The disclosures in Japanese Patent Application Publications Nos. 2003-162901 and H5-107529 prevent dust from entering by attaching the casing of the liquid crystal module to the liquid crystal panel and the diffuser plate. However, this method is difficult to apply to a liquid crystal module in which a catch is formed on the casing and the diffuser plate is fitted onto this catch as discussed above. More specifically, it is extremely difficult to attach a member in a tiny gap between the catch and the diffuser plate. Therefore, work efficiency is compromised. Furthermore, providing such a member increases the manufacturing cost. Also, there is the danger that the catch may be deformed or bent in the course of attaching the member to the catch. It is particularly difficult to repeatedly attach and remove the diffuser plate.
The Japanese Patent Application Publication No. H6-139766, meanwhile, discloses a structure in which dust is prevented from entering by using an insulating member and a circuit board. However, when a structure thus involving a number of parts is applied to a liquid crystal module, it increases the manufacturing cost, and also makes the liquid crystal module undesirably larger and thicker. Furthermore, the use of solder increases manufacturing costs and lowers work efficiency.
In view of the above, it will be apparent to those skilled in the art from this disclosure that there exists a need for an improved liquid crystal module that overcomes the problems of the conventional art. This invention addresses this need in the art as well as other needs, which will become apparent to those skilled in the art from this disclosure.